Retractile cutter blades assembly for lawn mowers



June 7, 1960 s. .1. KONTIS 2,939,264

RETRACTILE CUTTER BLADES ASSEMBLY FOR LAWN MOWERS Filed May 5, 1958 INVENTOR 50705 J. K0/vr/5 ATTORNEY j United States Patent RETRACTILE CUTTER BLADES ASSEMBLY FOR LAWN MOWERS Sotos J. Kontis, 722 Stiles Ave., Tallahassee, Fla. 7

Filed May 5, 1958, Ser. No. 732,954 1 1 Claim. (Cl. 56-295) This invention relates to lawn mowers, and more particularly to retractile cutter blade assemblies for lawn mowers.

In a class of lawn mowers, the cutter blades are carried by and extend outwardly from a rotary support, such as a plate, with the plate generally rotating on a vertical axis, whereby the sweep of the blades is horizont-al.

An important object of the invention is to provide a retractile cutter blade assembly for lawn mowers in which the blades normally extend radially from the rotary support and are retained extended by centrifugal force during normal cutting operations but, when a blade encounters an object which blocks its path and cannot be severed, the blade will move out of the path of the object and thus prevent damage to the blade and/or the support or means, as a motor, for rotating the support.

Another important object is to provide a retractile cutter blade assembly in which not only the blade that encounters an object which it cannot sever, but all other blades of the assembly, will retract to the same degree and thus maintain the balance of the assembly as a whole. This will prevent wear on bearings and eliminate a jerky operation of the assembly.

A further important object is to provide an assembly as stated which is easily disassembled for repairs or replacements, and includes no complicated parts or parts apt to get out of order.

Furthermore, an important object is to provide a doubleedged retractile blade which may be turned over and an unused cutting edge positioned so as to function during operation of the assembly.

Other objects and advantages of the invention will be apparent during the course of the following detailed de- ,scription of the invention, taken in connection with the accompanying drawing, forming a part of this disclosure, and in which drawing:

Figure l'is a vertical sectional view of the retractile cutter blade assembly coupled to a portion of means for rotating the assembly.

Fig. 2 is a horizontal sectional view, substantially on the line 22 of Fig. 1.

Fig. 3 is a top plan view of a blade retaining yoke of the assembly.

Fig. 4 is a bottom plan view of a power mower equipped with the retractile cutter blade assembly.

In the drawing, wherein for the purpose of illustration is shown a preferred embodiment of the invention and wherein similar reference characters designate corresponding parts throughout the several views, the letter A designates a vehicle, and B the retractile cutter blade assembly.

The vehicle A is shown as a conventional power driven lawn mower, including a chassis having a floor plate 11, the bottom face of which is shown in Fig. 4, and which chassis supports means 12 (Fig. 1) for rotating the retractile cutter blade assembly B. Such means may be a conventional internal combustion engine (not shown) Pat'entedlJune 7, 1960 with conventional rotor connection with the assembly B by way of the shaft '13, which extends downwardly through the floor plate 11, and coupling member 14,

I which extends below the floor plate and which is shown,

by way of example, as a plate integral with the shaft and provided with a plurality'of bolt shank accommodatin'g openings 15 or the like. The chassis 10 is shown as movable in a horizontal plane on ground rollers '16, 17, 18 and19, while the coupling member 14 rotates on a 'vertical axis. r

The retractile cutter blade assembly B includes support means 20 which is shown as a rotatable body portion '21, which is preferably a circular plate or disc having a substantially fiat upper face 22 from which extends upwardly an axially-disposed spindle or pivot member 23," and .a plurality of spaced-apart spindles or pivots, such as 24 and 25, disposed between the central spindle 22 and the peripheral edge 26 of the 'body portion 21. In the example shown, there are two spaced-apart pivots. They are spaced-apart at In addition, there are a plurality of stops, such as the stops 27, 28, 29 and 30, which are adapted to limit movement of the cutter blades to be subsequently described. The stops 27 and 28 are adapted to cause the blades to take positions radially of the body portion 21, when the cutter is in rotation, and the stops 29 and 30 limit retraction of the blades.

Swingably supported by the means 20 are the cutter means 35, which in the example shown, are two subst-antialelongated blades 36. The blades are substantially alike in weight, shape and size and gradually increase in width from their inner ends 37- to their outer ends 37, with the two cutting edges 38 of each blade diverging toward the outer end 37 of the respective blade. This provides a blade best suited for centrifugal action. Preferably integral with each blade is a sector g'ear'39, with the teeth 44 thereof extending for at least 180 and preferably, somewhat beyond 180 as may be seen in Fig. 2. Each sector gear is provided with a vertical opening 40 to accommodate either of the spindles 24 or 25 for rotation of the sector gear. It will benoted that means 41 is provided to indicate the relative positions of the sector gears with the central gear 42 to be described. For example, the means 41 may be small indentations onboth side faces of two adjacent teeth 44. The two indentations of each sector gear are spaced a subsequently equal distance from the longitudinal axis of the blade, which axis intersects the axis of rotation of the sector gear. The central gear 42 is'mounted for rotation upon the spindle 23 and its teeth 43 mesh with the teeth 44 of the sector gears 39. It will be noted that means 46 are provided on the centralgearto assist in positioning the blades 36 correctly (with their longitudinal axis in alignment). The means 46 may be slight indentations in two upper'side faces of teeth 43 disposed 180 apart. By positioning the means 41 and 44 as in Fig. 2, proper positioning of the blades are assured. There is provided in the upper side face of the gear 42 a socket 45 for securing one end portion of a spring 60 to be later described.

Hold down means 50 for the blades 36 may comprise a yoke 51, shown best in Fig. 3, taken with Fig. 1, having a body portion with a circular central opening 52 and two upwardly-extending bosses or flanges 53 on either side of and spaced from the opening 52 and each having a circular opening 54, and screw threaded radially-extending openings 55 from the exterior of bosses to the openings 54. The opening 52 is adapted to accommodate both a portion of the spindle 23 as well as the lower portion of the spring 60 and the openings 54 accommodate the upper end portions of the spindles 24. Set screws 56 are adapted to extend through the opening 55 to bear against the spindles 24 when the yoke 51 is in position as in Fig. 1.

Loosely surrounding the lower portion of the spindle 3 23, is an expansion helicalspring 60, one function of whiehjsto cause some resistance oft-he blade t the ut- 7 ting operation, having a downturned portion 61 of the lowermost terminal coil and an upturned portion 62 of the ,thereagainst. By lowering the set collar.65 tension on the I spring :60 be increased and raising the collar will decrease-such tension.

:u-Apovesfthetset'collar 65 is couplingmeans 70, conilprising a bqdy portion'which maybe a flat disc171 pro vided a central hub or collar .72fintegral therewith providing a socket 73 to snugly receive the upper end por-l tion "of the spindle 23, and through which radially extend screw-threaded bores to extend set screws 74116 bear against the spindle 23. Inraddition, I may proivid'e a key '72! carried by the collar72'and projecting ,into the socket t t e cut ng ac iq vflfth blad$- 7310 fit snugly into a suitable keyway in the free end 7 portion of the spindle 23. By means of nuts and bolt assemblies 75, themeans 14 and 70 may be coupled together with portions of the shanks of the bolts extending through aligning openings 76 in the disc 71 and openings 15 inthe coupling member 14.

Upon rotationof the shaft 13 and coupling member 14,

Q the plate 21 will also rotate with them and centrifugal force totend to cause the blades 36 to take the positions as in Fig.4; and the blades will be in positon'to out. If one blade-comes into contact with an'obstacle and cannot "cutinto itithe blade will retract and thiswillcause a rota- :tioniof the sector gear 39 integral therewith which, in

7 turn; will'cause a partial rotation of the gear 42 against V the tensionfof the spn'ng'60; and theg'ear cause partial rotation ofthe' other sector gear and retraction" of ithe blades integral therewith to a degree of retraction eq'uallto that of the first-mentioned blade. The blades can retract until the edges'jc'ontact the stops 29 and 3i) frespectively which contact is suflicient fort-the blades'to clear the obstacle and even cause'the blades toplear the a periphery 27 Rotation of the gear 42 willcause winding up (causing increased tension upon) the spring 60 but when the obstacle is cleared," the spring unwind and: cause the gear 42 "to restore the blades to their tended positions .1

' Thef connection of the blades with the gear wheel provides a strong connection free of fragile'parts or'partsapt to lose their ability to functionp'roperly, such as springs. With the blades 36 increasing in weight until their greatest weightis at their outer ends, the construction will tend to cause the'blades to extend as in Fig. 2, upon rotation of the apparatus B, and maintain their positions so as to cut grass and the like, despite the resistance of the grass Various changes may be made to the form of the invention herein shown and described without departing'from the spirit of the invention or scope of the claim.

I claim:'

A lawn mower retractile cutter blade assembly including a rotatable disc having'fan agiially-disposed spindle and a p u a o g aq dpa t vot nsex m n u wa d in parallelism fi'onr faee offsaid disc; a" plurality "of double-edged cutterbladesfouje for each pivot pin, and each-blade havifi'g'cutter portions extending outwardly of said disc and havingjasectorgear integral therewith at its inner eaia'anarotatanlwnreuntedu s]: a pivot'pin, with portions of th e lengths of thej'piyot pins extending through said sector gears and with the free end portions of said pivot pins extending outwardly thereof; a gear wheel rotatably mounted on said spindle and in mesh with all oflsaid sector'gears, a yokehaving a centralopengiaccomrnoda i g a portion of d spindl n withthc wall of said central opening spaced from said spindle, said yoke bridgingfthe space'between said pivot pins and having a plurality of openings adjacent the outer ends of said yoke to accommodate parts of the free .end portions of said p o p sfan a p rality of upwardly-ex endin tubular bosses, surrounding each of the last-named openings and accommodating ,otherpartsfof the free endportions ,of'said pivot'pins, each of'said bosses being provided with a radially-extending screw-threaded "opening therethrough, and a set screw for each-of. said screwthreaded openings and having free end means for bearing against said pivot pins; means carried byJsaid spindle to couple said assembly to a'rotor'of a lawn mower; and means to .retardrot'ation of said gear wheel during movement from a first rotative position to a second rotative position andrestore said gear wheel ,to said first position,

said bosses extending upwardly with their longitudinal 'axes in parallelism with the longitudihal axisgofisaid spring. andsaidbosses faeing' and spaeed' from'said spring. 

